This invention is related to apparatus for polishing a prescription eyeglass lens formed of a plastic, such as polycarbonate or CR-39, and more particularly to a polishing pad having a felt-like cloth frictionally mounted on the pad, without the use of an adhesive.
Plastic lens blanks conventionally have a generated concave prescription surface. After the back surface has been generated, the lens is normally treated by abrasive pads in a finishing machine, and then polished in a final step. Both the prepolishing step and the polishing step are achieved in vibratory machines using adhesive paper-like pads, mounted in a lap to engage the lens surface while using a slurry. The lap has a convex curvature, generally corresponding to the concave curvature of the lens. Consequently, several laps are required in the labs inventory to accommodate the variety of lens curvatures.
The polishing pad is a thin, felt-like flexible element, having a series of slots which permit the polishing pad to be mounted on laps having different curvatures. The polishing pad is attached to the lap by an adhesive back. Each polishing pad is used to polish a single lens, then must be peeled from the lap and replaced for the next lens.
The removal and mounting of a conventional polishing pad is a time-consuming process, particularly in a laboratory where hundreds of lenses are processed each day. The required mounting and removal time is substantial. In fact, some workers have their time primarily devoted to mounting and peeling the polishing pads. Further, since the polishing pad is useful for only a single lens, a substantial inventory of polishing elements is necessary.